The coastal peoples generally, and those of the Gold Coast in particular, were certainly prepared to welcome the merchants of other European nations so as to decrease their dependence on the Portuguese. The first Europeans effectively to break into the Portuguese monopoly of sea trade with western Africa were the Dutch, who had been some of the principal distributors in northwestern Europe of the Asian, African, and American produce imported into Portugal and Spain. After the northern Netherlands had revolted against Spanish rule, however, and Philip II of Spain (who since 1580 had been king of Portugal also) had sought to punish the Dutch merchants by excluding them from the Iberian ports, they were stimulated to organize oceanic trading ventures of their own and from 1598 established on the Gold Coast the first Dutch trading posts in western Africa.

The principal targets for Dutch aggression, however, were in the East Indies and in the Americas, and the effective assertion of Dutch power against Portugal in western Africa was a by-product of the success of the Dutch West India Company in destroying Spanish naval power in the Caribbean and in embarking on the conquest of the plantation colony that the Portuguese had established in Brazil. As a result, by the end of the 1630s the Dutch had established themselves as principal suppliers and customers of the Spanish plantations in the Caribbean, while in Brazil they were themselves in possession of a plantation colony.

The production on American plantations of tropical produce, of which sugar was the most important, and especially the marketing of this produce in western Europe, were extremely profitable activities. But plantation agriculture in the tropics required large and regular supplies of cheap labour. America did not have these, but, just across the Atlantic, western Africa seemed to have relatively great quantities of productive labour. As early as the 1440s, the Portuguese had begun to transport some African slaves to supplement the meagre labour resources of their own country (especially of the southern provinces they had reconquered from the Moors), and their own plantations in Madeira, the Cape Verde Islands, and, ultimately, on the islands of the Gulf of Guinea had come to be dependent on African slave labour. The Spaniards, and subsequently other Europeans, in America thus naturally came to look to Africa to make good their labour shortage, and a slave trade to the Caribbean had commenced on a small scale in the 1520s.

Spain had little in the way of trade in Africa itself, so the authorities gave out contracts for the supply of slaves to other merchants, and the ultimate suppliers were usually Portuguese. From the 1570s onward, Portugal’s slave traders had a further American market in their own colony of Brazil. The large slave population on their Gulf of Guinea islands was getting out of control, with the result that many Portuguese planters were abandoning these islands and reestablishing their activities in Brazil.

By the time the Dutch West India Company entered the scene in the mid-1620s, in all probability about 400,000 slaves had been imported into the Americas, and the annual volume of imports had risen to about 10,000 a year. This was a sizable business compared with the earlier trades in African slaves to Europe (which had virtually ceased by the 1550s, when perhaps 50,000 slaves had been imported) or to the Atlantic and Gulf of Guinea islands (which by the 1620s had probably received rather more than 100,000 slaves, but whose imports were then less than 500 a year). The demand for slaves in the Americas was also beginning to increase rapidly. In the wake of the Dutch defeat of Spanish naval power, English and French colonists were beginning to settle the smaller Caribbean islands and were seeking to exploit their soils for tropical agriculture with as many slaves as possible, while Spanish official restrictions on the volume of slave imports in their territories were hardly effective.

The labour needs of the plantations it had conquered in Brazil made it imperative that the Dutch West India Company should begin to secure slaves from Africa, and it very quickly recognized that the supply of slaves to European colonists elsewhere in the Americas was an extremely profitable business. To ensure its sources of supply, the Dutch company embarked on the conquest of all the Portuguese bases on the western African shores. Some of these, for example the island of São Tomé in the Gulf of Guinea, were subsequently lost to it, but by 1642 the Dutch were firmly in possession of the Portuguese forts on the Gold Coast, and they dominated Europe’s trade with western Africa from Cape Verde to the Niger delta. By the 1660s probably as many as 15,000 African slaves were being landed in the Americas each year. Nearly half of this trade was Portuguese, for this nation had by then recovered its possessions in both Brazil and Angola and had a near monopoly of the trade south of the equator, but the remainder, the growing part, was in northern European hands.

The Dutch West India Company’s activities in the Atlantic slave trade aroused interest throughout the ports of northwestern Europe, and soon merchants from France, Britain, Germany, and Scandinavia, as well as private Dutch traders, were competing with the Dutch company. French and British competition soon became of major importance. Both countries were resentful of the growing economic power of the Netherlands that was based on foreign trade, and both possessed colonies in the Americas. Their governments decided that their colonists should not be dependent on Dutch merchants for their supplies of labour (nor, for that matter, for capital or for the marketing of their produce in Europe). Through grants of monopolies of their nations’ trade with western Africa or the West Indies, French and English merchants were encouraged to form companies strong enough to challenge the power of the Dutch West India Company, and these challenges were supported by the warships of their respective royal navies.

Between 1652 and 1713 there was a succession of wars involving France, Britain, and the Netherlands. The main battles were usually fought far away from Africa, but throughout the period the traders of each nation sought to increase the number of their trading posts on the western African coast and to deny trade to their rivals. A large number of new forts was built, and these forts were constantly changing hands.